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@inasawa(稲澤 祐一)

iPhoneからBLEのCurrent Time Serviceで現在時刻を取得する（M5StickC編）

Last updated at Posted at 2019-10-04

概要

M5Stack/M5StickC で現在時刻を取得する方法として NTP ではなく BLE で取得する方法を探していたところ Current Time Service というのがありました。とりあえず Pythonista で試し返ってくる時刻データの内容を確認するためのサンプルプログラムがこちら。
iPhoneからBLEのCurrent Time Serviceで現在時刻を取得する（Pythonista編）

M5StickC でも同様にということで試したのですが、いろいろ苦労することになりました。

  • スケッチ例の BLE_Client.ino は使いたいサービスをアドバタイズしているサーバに接続する方式ですが、iPhone の Current Time Service はアドバタイズされていない。
  • サーバのデバイス名で接続したかったが、スキャンしても名前が取得できない。
  • スキャンしたものから iPhone と思われるものに狙いを定めて（TxPower が 12 というのがそれらしかった）接続すると Service および Characteristic は見つかるが readValue しても中身が空。
  • ペアリングが必要らしいと悩んでいたところで M5StickC をサーバーとし、iPhone側からペアリングを行なった後に M5StickC をクライアントとしてペアリングした iPhone に接続する例を見つけ参考にさせていただいた。元は別途 NTP などで時刻合わせの想定だったけど、iPhone との BLE連携アプリなので Current Time Service での時刻取得が最適。
  • ペアリングしようとしても iPhone の設定アプリの Bluetooth画面に M5StickC のデバイス名が現れない。Bluetooth のテストアプリ（BLE Scanner等）では見え、そこで接続すると時刻取得に成功。
  • 一旦成功した後は Bluetooth画面に名前が現れているので、そこで接続操作を行えばよくなる。
  • その後、いろいろ試しているうちに成功した方法でも readValue しても中身が空になる現象が発生。ここで他の M5Stack で試したりしたが問題ない。ふと M5Burner で Erase してみたらその後は正常に値が取得できるようになった。

課題

環境

  • iPhone 6 iOS 12.4.2 (BLE Server)
  • M5StickC (BLE Client)

実行例

  1. M5StickC 側のアプリ実行後、iPhone側の設定アプリのBluetooth画面には現れない
  2. Bluetooth のテストアプリ（今回は BLE Scanner を使用）で Connect
  3. ペアリング要求画面が現れる
  4. 以降はBluetooth画面にも表示されるようになる

１． 2019-10-05-3 BLE Pairing.png ２．2019-10-05-4 BLE Pairing.png
３． 2019-10-05-5 BLE Pairing.png ４．2019-10-05-6 BLE Pairing.png

実行時のシリアルモニタ出力例

M5StickC initializing...OK
Start Advertising
MyServerCallbacks Server Connected: xx:xx:xx:xx:xx:xx
MyServerCallbacks Stop Advertising
Client Connecting to Server xx:xx:xx:xx:xx:xx
MyClientCallback Client Connected
Client Connected
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 0
Get Current Time from Server
The characteristic value length: 10  <-- ペアリング完了後に値が返る
2019-10-04 21:25:28.984 5 x02

TFT_Clock.ino 修正版のアナログ時計。
2019-10-05-2 TFT_Clock_M5StickC.jpeg

RTC.ino 修正版のデジタル時計。
2019-10-05-1 RTC_M5StickC.jpeg

M5StickCプログラム

M5StickC用のスケッチ例 TFT_Clock.ino はコンパイル時刻を最初の時刻としますが、BLE Current Time Serviceからの時刻取得処理を追加したプログラムです。

TFT_Clock.ino
/*
 An example analogue clock using a TFT LCD screen to show the time
 use of some of the drawing commands with the library.

 For a more accurate clock, it would be better to use the RTClib library.
 But this is just a demo. 

 This sketch uses font 4 only.

 Make sure all the display driver and pin comnenctions are correct by
 editting the User_Setup.h file in the TFT_eSPI library folder.

 #########################################################################
 ###### DON'T FORGET TO UPDATE THE User_Setup.h FILE IN THE LIBRARY ######
 #########################################################################

 Based on a sketch by Gilchrist 6/2/2014 1.0
 */
#include <M5StickC.h>

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//+++++ for Get Current Time from BLE Current Time Service +++++
//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include <BLEDevice.h>

#define LOCAL_NAME "M5StickC Clock"
static BLEUUID CTSserviceUUID("1805");
static BLEUUID CTScharUUID("2a2b");

BLEServer  *pServer = NULL;
BLEClient  *pClient = NULL;
BLEAddress *pBLEAddress = NULL;

class MyClientCallback : public BLEClientCallbacks {
  void onConnect(BLEClient* pclient) {
    Serial.println("MyClientCallback Client Connected");
  }

  void onDisconnect(BLEClient* pclient) {
    Serial.println("MyClientCallback Client Disconnected");
  }
};

class MyServerCallbacks: public BLEServerCallbacks {
  void onConnect(BLEServer* pServer, esp_ble_gatts_cb_param_t *param) {
    pBLEAddress = new BLEAddress(param->connect.remote_bda);
    Serial.printf("MyServerCallbacks Server Connected: %s\n", pBLEAddress->toString().c_str());
    pServer->getAdvertising()->stop();
    Serial.println("MyServerCallbacks Stop Advertising");
  };

  void onDisconnect(BLEServer* pServer) {
    Serial.println("MyServerCallbacks Server Disconnected");
  }
};
//--------------------------------------------------------------

#define TFT_GREY 0x5AEB

float sx = 0, sy = 1, mx = 1, my = 0, hx = -1, hy = 0;    // Saved H, M, S x & y multipliers
float sdeg=0, mdeg=0, hdeg=0;
uint16_t osx=120, osy=120, omx=120, omy=120, ohx=120, ohy=120;  // Saved H, M, S x & y coords
uint16_t x0=0, x1=0, yy0=0, yy1=0;
uint32_t targetTime = 0;                    // for next 1 second timeout

static uint8_t conv2d(const char* p); // Forward declaration needed for IDE 1.6.x
uint8_t hh=conv2d(__TIME__), mm=conv2d(__TIME__+3), ss=conv2d(__TIME__+6);  // Get H, M, S from compile time

boolean initial = 1;

void setup(void) {
  M5.begin();
  // M5.Lcd.setRotation(0);

  //M5.Lcd.fillScreen(TFT_BLACK);
  //M5.Lcd.fillScreen(TFT_RED);
  //M5.Lcd.fillScreen(TFT_GREEN);
  //M5.Lcd.fillScreen(TFT_BLUE);
  //M5.Lcd.fillScreen(TFT_BLACK);
  M5.Lcd.fillScreen(TFT_GREY);

  M5.Lcd.setTextColor(TFT_WHITE, TFT_GREY);  // Adding a background colour erases previous text automatically

  // Draw clock face
  //M5.Lcd.fillCircle(120, 120, 118, TFT_GREEN);
  //M5.Lcd.fillCircle(120, 120, 110, TFT_BLACK);
  M5.Lcd.fillCircle(40, 40, 40, TFT_GREEN);
  M5.Lcd.fillCircle(40, 40, 36, TFT_BLACK);

  // Draw 12 lines
  for(int i = 0; i<360; i+= 30) {
    sx = cos((i-90)*0.0174532925);
    sy = sin((i-90)*0.0174532925);
    x0 = sx*38+40;
    yy0 = sy*38+40;
    x1 = sx*32+40;
    yy1 = sy*32+40;

    M5.Lcd.drawLine(x0, yy0, x1, yy1, TFT_GREEN);
  }

  // Draw 60 dots
  for(int i = 0; i<360; i+= 6) {
    sx = cos((i-90)*0.0174532925);
    sy = sin((i-90)*0.0174532925);
    x0 = sx*34+40;
    yy0 = sy*34+40;
    // Draw minute markers
    M5.Lcd.drawPixel(x0, yy0, TFT_WHITE);

    // Draw main quadrant dots
    if(i==0 || i==180) M5.Lcd.fillCircle(x0, yy0, 2, TFT_WHITE);
    if(i==90 || i==270) M5.Lcd.fillCircle(x0, yy0, 2, TFT_WHITE);
  }

  M5.Lcd.fillCircle(40, 40, 2, TFT_WHITE);

  // Draw text at position 120,260 using fonts 4
  // Only font numbers 2,4,6,7 are valid. Font 6 only contains characters [space] 0 1 2 3 4 5 6 7 8 9 : . - a p m
  // Font 7 is a 7 segment font and only contains characters [space] 0 1 2 3 4 5 6 7 8 9 : .
  //M5.Lcd.drawCentreString("M5Stack",120,260,4);

  //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  //+++++ for Get Current Time from BLE Current Time Service +++++
  //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  BLEDevice::init(LOCAL_NAME);
  BLEDevice::setEncryptionLevel(ESP_BLE_SEC_ENCRYPT);
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  pClient = BLEDevice::createClient();
  pClient->setClientCallbacks(new MyClientCallback());

  pServer->getAdvertising()->start();
  Serial.println("Start Advertising");

  while (pBLEAddress == NULL) {
    delay(100);
  }
  Serial.printf("Client Connecting to Server %s\n", pBLEAddress->toString().c_str());
  pClient->connect(*pBLEAddress);
  Serial.println("Client Connected");
  Serial.println("Get Current Time from Server");
  while (true) {
    std::string value = pClient->getValue(CTSserviceUUID, CTScharUUID);
    Serial.printf("The characteristic value length: %d\n", value.length());
    if (value.length() == 10) {
      // 10 byte data
      // byte 0,1 Year (byte1*256+byte0)
      // byte 2   Month
      // byte 3   Day
      // byte 4   Hours
      // byte 5   Minutes
      // byte 6   Seconds
      // byte 7   Day of Week (Monday = 1, ... Sunday = 7)
      // byte 8   1/256th of a second (milliseconds = byte8*1000/256)
      // byte 9   Adjust Reason
      //          bit 0: Manual time update
      //          bit 1: External reference time update
      //          bit 2: Change of time zone
      //          bit 3: Change of DST (daylight savings time)
      hh = value[4];
      mm = value[5];
      ss = value[6];
      Serial.printf("%d-%02d-%02d %02d:%02d:%02d.%03d %d x%02x\n",
                     value[1] << 8 | value[0], value[2], value[3],
                     value[4], value[5], value[6], value[8]*1000/256, value[7], value[9]);
      break;
    }
    delay(100);
  }
  //--------------------------------------------------------------

  targetTime = millis() + 1000; 
}

void loop() {
  if (targetTime < millis()) {
    targetTime += 1000;
    ss++;              // Advance second
    if (ss==60) {
      ss=0;
      mm++;            // Advance minute
      if(mm>59) {
        mm=0;
        hh++;          // Advance hour
        if (hh>23) {
          hh=0;
        }
      }
    }

    // Pre-compute hand degrees, x & y coords for a fast screen update
    sdeg = ss*6;                  // 0-59 -> 0-354
    mdeg = mm*6+sdeg*0.01666667;  // 0-59 -> 0-360 - includes seconds
    hdeg = hh*30+mdeg*0.0833333;  // 0-11 -> 0-360 - includes minutes and seconds
    hx = cos((hdeg-90)*0.0174532925);    
    hy = sin((hdeg-90)*0.0174532925);
    mx = cos((mdeg-90)*0.0174532925);    
    my = sin((mdeg-90)*0.0174532925);
    sx = cos((sdeg-90)*0.0174532925);    
    sy = sin((sdeg-90)*0.0174532925);

    if (ss==0 || initial) {
      initial = 0;
      // Erase hour and minute hand positions every minute
      M5.Lcd.drawLine(ohx, ohy, 40, 40, TFT_BLACK);
      ohx = hx*15+40;    
      ohy = hy*15+40;
      M5.Lcd.drawLine(omx, omy, 40, 40, TFT_BLACK);
      omx = mx*20+40;    
      omy = my*20+40;
    }

    // Redraw new hand positions, hour and minute hands not erased here to avoid flicker
    M5.Lcd.drawLine(osx, osy, 40, 40, TFT_BLACK);
    osx = sx*25+40;    
    osy = sy*25+40;
    M5.Lcd.drawLine(osx, osy, 40, 40, TFT_RED);
    M5.Lcd.drawLine(ohx, ohy, 40, 40, TFT_WHITE);
    M5.Lcd.drawLine(omx, omy, 40, 40, TFT_WHITE);
    M5.Lcd.drawLine(osx, osy, 40, 40, TFT_RED);

    M5.Lcd.fillCircle(40, 40, 2, TFT_RED);
  }
}

static uint8_t conv2d(const char* p) {
  uint8_t v = 0;
  if ('0' <= *p && *p <= '9')
    v = *p - '0';
  return 10 * v + *++p - '0';
}
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